can you explain briefly what it does
because with 3gb switch it used to take 2.8gb now we have this -g384 and sqlserver
is using only 2.5gb is there a way where we can see how effectively that 384mb is used

Initially -g option is used for memory_to_reserve which specifies memory to reserve for other applications running within SQL process.

At our end when we had performance issues and observation suggests that some SQL servers stay up longer than others before the backups start failing and even when any connection is attempted.

Although I initially suspected a memory leak was causing the problem, and it proved that the problem is solely down to memory fragmentation.

MS Support suggested to alleviate the problem is to increase the MemToLeave area using the '-g' SQL Server startup switch. The proposal was to increase the value from the default value of 128 to 256.

MemToLeave on SQL 2000 is 256 MB, and out of 256, SQL uses some for its own executable files and dynamic link libraries. I think MEMORY counters in PERFMON/SYSMON will help to assess. The server configurations such mas "max memory", "min memory" and "working set" can only affect the size of buffer pool. They can't control the size of MemToLeave.